[Clinical experiences with the double jet technique superimposed HFJV (high frequency jet ventilation) during larygotracheal surgery]. / Klinische Erfahrungen mit der Doppel-Jet-Technik: Die Superponierte Hochfrequenz-Jet-Ventilation in der Larynxchirurgie.

OBJECTIVE: Single-frequency high-frequency jet ventilation (HFJV) is an established ventilatory technique during laryngotracheal surgery. This study describes the clinical use of combined HFJV, characterised by the simultaneous application of a low-frequent (LF) and a high-frequent (HF) jet stream. METHODS: Two jet streams with different pulsatile frequency (HF approx. 10 Hz, LF 10-30 bpm) and adjustable driving pressures were applied supraglottically by means of a special jet laryngoscope in patients undergoing elective laryngotracheal surgery during total intravenous anaesthesia. HFJV was performed using a pneumatic or electronic jet respirator connected to the central gas supply. RESULTS: 134 patients were submitted to tubeless HFJV applying the double-jet technique using the jet-laryngoscope. Duration of HFJV was < or = 30 min in 60 patients (45%), between 30 and 60 min in 49 patients (36%), and > or = 60 min in 25 patients (19%). Classification into 3 groups according to weight ((I < 65 kg, II = 65-84 kg, III > or = 85 kg) using driving pressures of 1.52 +/- 0.47 bar, 1.64 +/- 0.78 bar, and 1.69 +/- 0.67 bar for the HF jet and 1.78 +/- 0.54 bar, 1.90 +/- 0.48 bar, and 2.00 +/- 0.49 bar for the NF jet demonstrated differences in paO2 (156 +/- 45 [I] vs 126 +/- 34 [II] vs 96 +/- 18 [III] mm Hg) and paCO2 (42 +/- 9 und 44 +/- 8 vs 48 +/- 8 mm Hg) using comparable FjetO2 (0.6 +/- 0.2). Supraglottic pressures were 11.6 +/- 6.8, 11.5 +/- 7.0, und 12.6 +/- 7.1 cm H2O (I-III). No ventilator-related adverse events were observed. CONCLUSION: Tubeless supraglottic HFJV utilizing two jet streams with low and high frequency was effective in patients during laryngotracheal surgery. The application of two jet streams results in phasic changes of airway pressures between an inspiratory and expiratory pressure level, and facilitates application of enlarged tidal volumes. As demonstrated, oxigenation and ventilation is compromised by increased body weight. Superimposed HFJV (double-jet technique) enables the supraglottic ventilation of heavy patients and/or in the presence of airway stenoses during laryngotracheal surgery without need to use maximum driving pressures.

High-frequency jet ventilation in European and North American institutions: developments and clinical practice.

Respiratory support with high-frequency jet ventilation has been advocated during airway surgery or to improve pulmonary mechanics and gas exchange in patients with bronchopleural fistulae or pulmonary insufficiency. Despite a large body of published evidence describing its benefits as an alternative ventilatory approach in anaesthesia and intensive care medicine, its application has not gained widespread acceptance and is restricted to specialized centres. To review the literature on high-frequency jet ventilation in European and North American institutions, we performed a search in a computerized database (MEDLINE) covering the period from 1990 until the present time, describing the use of high-frequency jet ventilation in over 7000 patients. Various modes to apply high-frequency jet ventilation during airway surgery have been established, but its value in intensive care is controversial. We report our experience with combined high-frequency jet ventilation and provide guidelines for its safe application.

Tubeless combined high-frequency jet ventilation for laryngotracheal laser surgery in paediatric anaesthesia.

BACKGROUND: High-frequency jet ventilation (HFJV) is an alternative ventilatory approach in airway surgery and for facilitating gas exchange in patients with pulmonary insufficiency. We have developed a new technique of combined HFJV utilising two superimposed jet streams. In this study we describe the application of tubeless supralaryngeal HFJV during laryngotracheal laser surgery in infants and children. METHODS: Tubeless combined HFJV characterised by the simultaneous supralaryngeal application of a low-frequency (LF) and a high-frequency (HF) jet stream was evaluated in a clinical study in 10 children undergoing elective laryngotracheal CO2 laser surgery. Additionally, pressure and flow characteristics were determined with the use of a paediatric test lung. HFJV was applied by means of a modified Kleinsasser laryngoscope with integrated metal injectors. In addition to pulse oximetry, monitoring of ECG, heart rate and blood pressure, supraglottic airway pressure was measured and arterial blood gases were analysed. RESULTS: Tubeless combined HFJV was used in 10 infants and children (mean age 4.6 yr, range 2 months-10 years) undergoing 17 consecutive endoscopic procedures with CO2 laser microsurgery of the larynx or the trachea under general anaesthesia. The mean duration of supralaryngeal HFJV was 46 min (range 15-75 min). Mean driving pressures of the HF and the LF jet streams were 0.75 bar and 0.95 bar, respectively. Inspiratory oxygen ratios were in the range 0.4-1.0. HFJV resulted in mean PaO2 and PaCO2 values of 19.7 kPa and 6.1 kPa, respectively. No complications during HFJV were observed. In the test lung, combined HFJV applied with driving pressures of 0.7-1.0 bar and 0.9-1.2 bar for HF and LF jet ventilation, respectively, resulted in maximum peak and baseline distal airway pressures of 17.6 cm H2O and 5.4 cm H2O, respectively. CONCLUSION: The application of the combined double frequency HFJV was effective in maintaining gas exchange in the presence of laryngeal or tracheal stenoses. It provided good visibility of anatomical structures and offered space for surgical manipulation, avoiding the use of combustible material inside the larynx or trachea.

Application of SHFJV for surgical procedures.

Using SHFJV in combination with the jet laryngoscope it is possible to ventilate patients for laryngeal surgery with out the necessity for any kind of endotracheal tube or catheters. This technique can also safely be applied in patients with underlying pulmonary or cardiac disease or in obese patients. Patients with laryngeal stenosis can be ventilated from above the stenosis eliminating the danger of barotrauma. The laser can be used at any time the surgeon desires without any additional protective measures. The SHFJV can be used for tracheobronchial stent insertion. Only in cases were the glottis can not be visualized through the jet laryngoscope sufficient ventilation is not ensured and therefore transtracheal high frequency ventilation is the technique of choice.

High frequency ventilation techniques in ARDS.

High frequency ventilation techniques are not applied as routine measures but are still regarded as lastditch efforts in treating patients with severe ARDS or with extensive bronchoplural fistula when conventional mechanical ventilation is not capable in providing sufficient gas exchange. High frequency ventilation techniques can be used in patients with septicemia or recent cerebral bleeding, which is a contraindication for ECMO, or in patients with increased ICP. We believe that high frequency ventilation techniques provide an important therapeutic tool in the treatment of pulmonary insufficiency since the hardware requirement is minimal and, after a brief explanation, the application is easy.

[Superimposed high-frequency jet ventilation (SHFJV) in the administration of NO. Technical basis and early clinical results with ARDS]. / Superponierte Hochfrequenz Jetventilation (SHFJV) unter Verwendung von NO. Technische Grundlagen und erster klinischer Einsatz bei ARDS.

The mortality of patients with acute respiratory distress syndrome (ARDS) is still above 50% despite continuous progress in intensive care medicine. Recent therapy regimens such as the extra corporeal life support (ECLS), permissive hypercarbia, high-frequency ventilation techniques and inhaled nitric oxide (NO) are being applied. All of the above techniques are aimed at different parts of the problems caused by ARDS. This study was designed to evaluate the possible additive benefits of superimposed high-frequency jet ventilation (SHFJV) and inhaled NO. METHODS. In experiments on a lung simulator it was demonstrated that it is possible to administer exact amounts of NO using a computer-controlled system with a feedback loop (Pulmonox) using the SHFJV. Applying the therapeutic reference point of 20 ppm of NO, the deviation was +/- 3 ppm at this setting. CASE REPORT. After successfully concluding our experiments, this combined therapy concept was applied in a patient with terminal ARDS. Under CMV, paO2 was 69.4 mm Hg and the oxygen saturation 88.3% with a F1O2 of 1.0. Significant improvement was observed within 30 min after starting SHFJV with inhaled NO (paO2 282.9 mm Hg; oxygen saturation 99.5%). There were no differences observed in hemodynamic parameters between CMV and SHFJV. Although the pulmonary status of the patient improved, the patient died due to therapy-resistant hemodynamic failure. CONCLUSION. It will take further studies to judge whether the success of this new ventilation strategy is reproducible and if the improvement of the oxygenation is more pronounced when adding inhaled NO to SHFJV than when each technique is applied separately.

[Preliminary experiences with superimpoposed high-frequence jet ventilation in intensive care]. / Erste Erfahrungen mit der Superponierten Hochfrequenz-Jetventilation in der Intensivmedizin.

The study aimed to evaluate whether superimposed high-frequency jet ventilation (SHFJV) is a useful tool in intensive care medicine to ventilate patients with pulmonary insufficiency. METHODS. SHFJV is the simultaneous application of low- and high-frequency jet ventilation performed using a specially designed ventilator. SHFJV versus conventional mechanical ventilation (CMV) was were applied in three groups of patients. Group 1 (Gr 1) included patients without pulmonary insufficiency; group 2 (Gr 2) patients had moderate and those in group 3 (Gr 3) had severe pulmonary insufficiency. RESULTS. In Gr 1 and Gr 2, SHFJV was associated with a significant decrease in mean airway pressure (mPAW 12.9 vs. 13.3 mm Hg, P < 0.05). In Gr 3 oxygenation was significantly better with SHFJV (mean paO2 140.1 vs. 109.9 mm Hg, P < 0.05; mean FiO2 0.66 vs. 0.86, P < 0.05). Other parameters, such as maximum airway pressure (Pmax) and mean Paw, were significantly lower with SHFJV than CMV (mean Pmax 29.6 vs. 40.1 mm Hg, mean Paw 18 vs. 21.9 mm Hg, P < 0.05). Intrapulmonary shunt fractions showed a significant decrease with SHFJV (24.6 vs. 34.4, P < 0.05). CONCLUSIONS. Significant differences were observed primarily in Gr 3 patients, indicating that patients with severe pulmonary insufficiency may benefit from SHFJV. SHFJV may thus represent an alternative mode of ventilation in critically ill patients.

[Ventilation during tracheotomy in extensive, 90% laryngeal stenosis using superimposed high frequency jet ventilation via the jet laryngoscope]. / Beatmung während einer Tracheotomie bei langstreckiger, 90%iger laryngealer Stenose mittels superponierter Hochfrequenz Jet-Ventilation über das Jet-Laryngoskop.

In a 35-year old male patient with laryngeal carcinoma an acute respiratory insufficiency with early hypoxaemia developed due to massive laryngeal stenosis. An endotracheal intubation was not possible since the available lumen was too small. Tracheotomy using local anaesthesia was not possible since spontaneous respiration with a Venturi mask applying 100% oxygen was not sufficient and the patient was becoming restless and agitated due to the hypoxaemia. Transcutaneous jet ventilation was considered to be too risky since the needle would have to pass highly vascularised tumour tissue and the detection of such a small rest lumen would have been quite difficult. Ventilating the patient using a percutaneous catheter would have been very risky as well since, due to the massive stenosis, a sufficient expiration would not be likely and therefore was considered to carry a high risk of barotrauma. The patient was ventilated under general anaesthesia via a specially designed endoscopy tube with integrated jet nozzles applying superimposed high frequency jet ventilation above the stenosis. Since it was possible to achieve sufficient ventilation during the inspection of the larynx the jet laryngoscope was left in place and the supporting apparatus was covered with sterile drapes. The tracheotomy was performed using the superimposed high frequency jet ventilation. Throughout the procedure oxygenation and ventilation were adequate. The laryngectomy performed several days later revealed a cauliflower type protrusion into the tracheal lumen and a 5 cm long stenosis of the larynx with a lumen of 3 mm.

[Anesthesia in acute respiratory tract obstructions caused by high degree laryngeal and tracheobronchial stenoses]. / Anästhesie bei akuten Atemwegsobstruktionen infolge hochgradiger laryngealer und tracheo-bronchialer Stenosen.

UNLABELLED: Stenotic process of the laryngeal and/or tracheobronchial system may lead to dyspnoea which can become life threatening. OBJECTIVE: The object of our study was to determine whether sufficient gas exchange can be ensured in patients with a massive stenosis of the respiratory tract applying the Superimposed High-Frequency-Jet-Ventilation (SHFJV) via the jet laryngoscope. Further, it was to be determined whether SHFJV can be applied for insertion of endoluminal stents into the tracheo-bronchial system. METHOD: SHFJV was applied using the Bronchotron-ventilator (capable of generating simultaneous low frequency and high frequency jets) and the laryngoscope, basically a modified endoscopy tube permitting simultaneous application of two jet modes. SHFJV was performed in 14 patients (including 4 children) suffering from massive laryngeal stenosis and in further 12 patients with stenosis of the tracheo-bronchial system. In all patients total intravenous anaesthesia was performed. RESULTS: In the patients with laryngeal stenosis the average paO2 was 117.5 +/- 43 mmHg, and the mean paCO2 47.3 +/- 11.6 mmHg. In the patients with stenosis of the tracheo-bronchial system the mean paO2 was 125 +/- 77 mmHg and the average paCO2 53.3 +/- 18 mmHg. CONCLUSIONS: The SHFJV technique presents the possibility to ventilate the patients continuously for surgical procedures even with massive stenosis of the respiratory tract. The application of SHFJV via the jet laryngoscope not only enables the anaesthesist to ventilate this group of patients but also helps the surgeon and therefore results in more safety for the patient.

[Jet ventilation superimposed on a special jet laryngoscope for endoluminal stent insertion in the tracheobronchial system]. / Superponierte Jet-Ventilation über ein spezielles Jet-Laryngoskop. Zur endoluminalen Schienung des Tracheobronchialsystems.

BACKGROUND: Stenotic processes of the tracheobronchial system may lead to dyspnoea that can become lift-threatening. To restore sufficient function of the blocked airway, a silicone stent can be inserted. The anaesthesia techniques used for this intervention so far have been complicated. The object of this study was to determine whether the super-imposed high-frequency jet ventilation (SHFJV) via the jet laryngoscope originally designed for microlaryngeal surgery can be utilized for endoluminal stent insertion. METHODS: In 12 patients with acute respiratory insufficiency (ASA 3-5) due to stenosis of the tracheobronchial system, an endoluminal silicone stent was inserted through the jet laryngoscope while the patient was ventilated using SHFJV: RESULTS: A significant rise in paO2 readings prior to the jet ventilation and subsequent measurements was observed. The CO2 elimination was good (average paCO2 31.5 +/- 7.5-53.1 +/- 14 mmHg). Variably high paCO2 readings during stent insertion were related to the respective surgical phases. At the end of the surgical manipulation, all patients had sufficient spontaneous ventilation. CONCLUSIONS: First clinical applications of the jet laryngoscope combined with superimposed jet ventilation for stent insertion demonstrated satisfactory results. Not only were the patients ventilated throughout the procedure, but CO2 elimination was also satisfactory. Superimposed jet ventilation provides a sufficient tidal volume with low ventilation pressures, and therefore oxygenation and CO2 elimination are unproblematic. SHFJV enables the anaesthetist to ventilate the patient nearly continuously with minimal phases of apnoea. The only apnoea phases, as with any other method, occur during surgical manipulation while inserting the stent and thus blocking the airway. We believe that the jet laryngoscope with SHFJV presents a distinct advantage for both anaesthetist and surgeon when inserting stents in the tracheobronchial system.

[Ventilation in laryngeal laser-surgical interventions using superimposed high frequency jet ventilation (SHFJV)--a further revision of jet ventilation technique for laryngeal interventions]. / Beatmung bei laryngealen laserchirurgischen Eingriffen mittels der Superponierten Hochfrequenz Jet-Ventilation (SHFJV)--Eine Weiterentwicklung der Jet-Ventilationstechnik für laryngeale Eingriffe.

In laser surgery of the larynx the surgeon and the anaesthesist have to compete for the limited space available. The surgeon requiring good visibility and an undisturbed operating area whereas the anesthetist has to ensure sufficient ventilation of the patient. Further, complications of anaesthesia and laser must be avoided. These requirements are met by using the jet-tube (jet-laryngoscope) with two integrated nozzles applying simultaneously low- and high-frequency jet-ventilation giving the surgeon total access to the area operated on, and at the same time enables safe ventilation of the patient. Of 334 operations with the tubeless ventilation technique 76 cases were laser surgical interventions. In 6 patients stenoses were enlarged. The average duration of the jet-ventilation was 25 +/- 10 minutes. The maximum duration of a laser surgical intervention was 140 minutes. The age distribution of the patients was 18 months to 82 years. In all patients pulmonary gas exchange was satisfactory. We believe that the advantage of the tubeless jet-ventilation is: optimal visibility and surgical freedom for the surgeon, no time limitation, even in very severe stenoses. Since no volatile anaesthetics or any type of endotracheal tube are applied there is no danger of interaction with the laser when using the SHFJV via the jet-laryngoscope. Application of the tubeless jet-ventilation technique is however limited if patients suffer from severe pulmonary obstruction; likewise highly obese patients and patients in whom massive bleeding occurs are not amenable to tubeless jet-ventilation.

Continuous spinal anesthesia with a microcatheter and low-dose bupivacaine decreases the hemodynamic effects of centroneuraxis blocks in elderly patients.

This prospective randomized study was designed to investigate the hemodynamic effects and quality of continuous spinal anesthesia (CSA) after rapid injection of a low dose of 0.5% bupivacaine through a 32-gauge microcatheter. The method was compared with continuous epidural (CEA) and single-dose spinal anesthesia (SSA). Seventy-seven elderly patients (ASA II-III) ranging from 57 to 94 yr old and undergoing lower limb surgery were assigned to CSA (n = 26), CEA (n = 26), and SSA groups (n = 25). In all three groups, mean arterial pressure (MAP) and heart rate (HR) were assessed continuously for 30 min after initial injection, as well as after every reinjection of local anesthetic in the CSA and CEA groups. Bupivacaine (0.5%) was used as a local anesthetic. The initial doses were 1 mL of CSA, 10 mL of CEA, and 3 mL of SSA. The reinjection doses were 1 mL of CSA and 5 mL of CEA. In the CSA group, MAP did not decrease, whereas in the CEA group, the maximum decrease was 15% +/- 3% (mean +/- SEM) for the initial injection, 12% +/- 2% for the first repetition, and 13% +/- 2% for the second repetition. In the SSA group, the largest decrease of MAP was 19% +/- 2%. All changes of MAP in the CEA and SSA groups were significantly larger compared with CSA group (P < 0.05). A total of seven patients in these two groups needed vasopressors due to a decrease of MAP of more than 30% from baseline values. Heart rate did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

[Continuous spinal anesthesia versus continuous epidural anesthesia in surgery of the lower extremities. A prospective randomized study]. / Kontinuierliche Spinalanaesthesie versus kontinuierliche Epiduralanaesthesie bei Operationen an den unteren Extremitäten. Eine prospektiv randomisierte Studie.

Continuous epidural anesthesia (CEA) is generally accepted as a routine method of regional anesthesia while there has been only limited application of continuous spinal anesthesia (CSA), due mainly to a lack of adequate spinal catheters. With the introduction of a new, ultra-thin spinal catheter (32 G) inserted via a thin puncture needle, some of the complications reported after CSA can be eliminated. We studied CSA versus CEA in lower-extremity operations. METHODS. We evaluated 33 patients in a prospective, randomized study. All were comparable with respect to age, anesthetic risk (ASA II-III), and pre-existing diseases. The only exclusion criterium was the presence of a coagulation disturbance. The CSA group consisted of 17 patients (mean age 75.5 +/- 0.1 year); 26 G puncture needle and 32 G catheter were used. The CEA group consisted of 16 patients (mean age 73.8 +/- 11.0 years); an 18 G puncture needle and 22 G epidural catheter with a stylet were inserted with the loss-of-resistance technique. Both catheters were placed with the patient in a sitting position and left in place for 24 h in order to administer local anesthetics (LA) for postoperative analgesia as required. Hemodynamic parameters-mean arterial pressure (MAP) and heart rate (HR)-were compared in each group at 5-min intervals for 30 min after administration of local anesthetic and at 10-min intervals during the operation. Additionally, the ECG, pulse oximetry, respiratory rate, diuresis, and blood gases were monitored. After placement of the catheter, patients in the CSA group received 1.9 ml (+/- 0.2) bupivacaine HCl 0.5%. Patients in the CEA group received 12.6 ml (+/- 2.5) bupivacaine HCl 0.5%. For statistical evaluation of the data we used mean values, standard deviation (+/-), the Kruscal-Wallis procedure, and Student's t-test for unpaired data. P less than 0.05 was considered significant. RESULTS. The mAPs in the CSA group generally remained lower than those of the CEA group. However, over the course of the operation as well as after repeated injections, the difference between the two groups decreased. Only at 5 min after administration of the initial dose was a statistically significant difference in blood pressures between the two groups observed. A clinically relevant, rapid decrease in blood pressure due to relatively high doses of LA was seen in 1 case in each group. The first reinjection of LA after the initial dose was after 1.9 h in the CSA group (bupivacaine HCl 0.5% 1 +/- 0.3 ml) and after 1.8 h in the CEA group (bupivacaine HCl 0.5% 4.5 +/- 1 ml). The total dose of bupivacaine in the CSA group was 0.18 ml/kg per hour versus 0.8 ml/kg in the CEA group. No post-dural puncture headache was observed in the CSA group. DISCUSSION. The catheter designed for CSA is easy to use, although because of its small diameter a certain manual dexterity is required. In addition, CSA resulted in a more rapid onset of action and more pronounced sensorimotor blockade than did CEA. Hemodynamic alterations and side effects were comparably low in both groups.